A toxin present in blue-green algae and consumed by sealife may be a cause of amyotrophic lateral sclerosis commonly known as Lou Gehrig's disease and other neurological diseases in humans who ingest contaminated water or seafood, according to research conducted by Dartmouth-Hitchcock Medical Center neurologist Elijah Stommel.
Stommel's research, which began in 2000, is still ongoing and was recently featured in Discover Magazine.
Beta-methylamino-L-alanine (BMAA), a compound found in cyanobacteria such as blue-green algae, has been thought to cause neurological defects since the 1960s, when foods containing the compound were linked to a neurological disease outbreak in Guam.
Stommel and students at Dartmouth Medical School plotted the addresses of about 800 ALS patients onto a computer map of northern New England and found that they were heavily concentrated around lakes and other bodies of water. The data indicate that ALS is 2.5 times more common in patients living within half a mile of bodies of water, Stommel said.
The subjects were the most densely clustered around Mascoma Lake, which is located in nearby Enfield, N.H. Between 2000 and 2006, nine patients living near the lake were diagnosed with ALS, according to a Dec.2009 paper published by Stommel and other DHMC researchers in Amyotrophic Lateral Sclerosis. Such prevalence is 10 to 25 times the normal ALS rate of two cases per 100,000 people per year.
Cyanobacteria, which thrive in ponds and lakes, may be increasing in volume due to eutrophication, caused by runoff from phosphates and nitrates found in lawn fertilizers, according to Stommel.
Stommel said BMAA may be linked to a number of neurological diseases including ALS, Parkinson's disease and Alzheimer's disease by accumulating in the brain, incorporating itself into brain tissue proteins and eventually causing them to collapse.
"If you put an amino acid into a protein that's not going to be there [naturally], it can have major effects," he said.
Stommel said people could potentially be ingesting BMAA in a number of different ways.
"We don't really know [the exact cause], but I assume its either through contamination of well water, aerosolization or possibly through eating fish," Stommel said. "If you are swimming in the water, you could ingest some of the water that way. It may be getting into the food chain. It's very hard to know."
Stommel said he plans to conduct further research with epidemiologists to examine common lifestyle factors amongst his patients. Stommel will distribute questionnaires to his patients to collect information about their diets, how much time they spend in the water and how long they have lived in the area.
"A lot of people move around a lot, so it's quite a difficult question to answer," Stommel said.
Stommel said he does not currently have enough information to declare certain types of seafood unsafe for consumption.
"I think it's conjecture at this point, but it's certainly something we're looking into," he said. "If you know that the fish has come from somewhere with a history of cyanobacterial blooms, I personally don't think I would eat the fish, but I am not telling other people not to because I don't really know for sure."
Stommel said he and other researchers will continue to investigate the subject, beginning by analyzing brain samples of ALS patients to see if they have elevated levels of BMAA.
Initial studies from the University of Miami have found high levels of BMAA in brain samples from ALS patients, according to a May 2011 Discover Magazine article profiling Stommel's research and published online on June 21.
Stommel said the growing abundance of cyanobacteria around the world could put people everywhere at risk if high levels of BMAA do cause neurological damage.
"I think it's a worldwide problem," he said. "Cyanobacteria are found everywhere."
